Electronic components often require a stable temperature to operate efficiently and effectively. Elevated operating temperatures reduce component efficiency and lifetime. Some electronic components also generate heat as they operate. This requires cooling to control component temperature. In traditional systems, heat is typically removed through local conduction and through convection to an external moving fluid. The assembly chassis is often made of metal and cooled by a liquid. This involves considerable weight and expense to machine the chassis and cooling channels.
Additional complications that arise with using a metal chassis because liquid cooling systems utilize a liquid that picks up heat from the hot components and then removes the heat from the chassis. That means the liquid should minimize contact with the chassis after it is heated by the hottest component. While designs may attempt to maximize thermal isolation, there is often a thermal loss as the heated liquid is cooled by the incoming liquid coolant.
Another complication is that a cooled metal chassis can also absorb heat from the environment rather than, or in addition to, absorbing heat from the heated components. This means that the liquid cooling system is cooling the entire equipment compartment rather than simply cooling an isolated electronic assembly, which reduces the efficiency and effectiveness of the liquid cooling system. Traditionally, to solve such problems designs thermally isolate a portion of the cooling system. This may be done by lining the coolant system with an insulating plastic sleeve. Other problems may arise with the use of metal chassis in conjunction with liquid cooling systems. For example, the metal chassis may be subjected to oxidation due to the presence of the liquid. This complication may also prevent the use of metal chassis in salty environments. A metal chassis may also be subject to galvanic corrosion where one metal corrodes preferentially to another when both metals are in electrical contact, in the presence of an electrolyte. Moreover, due to the density of various metallic alloys, a metal chassis may be very heavy.